import { window } from './facade/browser';

export type AvailableBsVersions = 'bs3' | 'bs4' | 'bs5';

interface IObjectKeys {
  [key: string]: boolean;
}

export interface IBsVersion extends IObjectKeys{
  isBs3: boolean;
  isBs4: boolean;
  isBs5: boolean;
}

export enum BsVerions {
  isBs3 = 'bs3',
  isBs4 = 'bs4',
  isBs5 = 'bs5'
}

let guessedVersion: AvailableBsVersions;

function _guessBsVersion(): AvailableBsVersions {
  if (typeof window.document === 'undefined') {
    return 'bs4';
  }
  const spanEl = window.document.createElement('span');
  spanEl.innerText = 'testing bs version';
  spanEl.classList.add('d-none');
  spanEl.classList.add('pl-1');
  window.document.head.appendChild(spanEl);
  const rect = spanEl.getBoundingClientRect();
  const checkPadding = window.getComputedStyle(spanEl).paddingLeft;
  if (!rect || (rect && rect.top !== 0)) {
    window.document.head.removeChild(spanEl);
    return 'bs3';
  }

  if (checkPadding && parseFloat(checkPadding)) {
    window.document.head.removeChild(spanEl);
    return 'bs4';
  }

  window.document.head.removeChild(spanEl);
  return 'bs5';
}

export function setTheme(theme: AvailableBsVersions): void {
  guessedVersion = theme;
}

// todo: in ngx-bootstrap, bs4 will became a default one
export function isBs3(): boolean {
  if (typeof window === 'undefined') {
    return true;
  }

  if (typeof window.__theme === 'undefined') {
    if (guessedVersion) {
      return guessedVersion === 'bs3';
    }
    guessedVersion = _guessBsVersion();

    return guessedVersion === 'bs3';
  }

  return window.__theme === 'bs3';
}

export function isBs4(): boolean {
  if (isBs3()) return false;

  if (guessedVersion) return guessedVersion === 'bs4';

  guessedVersion = _guessBsVersion();
  return guessedVersion === 'bs4';
}

export function isBs5(): boolean {
  if (isBs3() || isBs4()) return false;

  if (guessedVersion) return guessedVersion === 'bs5';

  guessedVersion = _guessBsVersion();
  return guessedVersion === 'bs5';
}

export function getBsVer(): IBsVersion {
  return {
    isBs3: isBs3(),
    isBs4: isBs4(),
    isBs5: isBs5()
  };
}

export function currentBsVersion(): AvailableBsVersions {
  const bsVer = getBsVer();
  const resVersion = Object.keys(bsVer).find(key => bsVer[key]);
  return BsVerions[resVersion as keyof typeof BsVerions];
}